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<div dir="ltr"><font color="#000000"><span style="caret-color: rgb(0, 0, 0); background-color: rgba(255, 255, 255, 0);">"Citation needed". :-) How is it clear that the vast majority are<br>
following this?</span></font></div>
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Uh, because the Internet works? Think about it. If an AS advertises prefixes that can’t be reached through all of its border routers, those prefixes would lose packets.
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<div>But I don’t need to provide a citation. The burden of proof is on the person making the assertion, and the assertion by Bill was that having disconnected prefixes in an AS was common. That’s the assertion that needs a citation. My statement is just an
opinion that <i>it is clear that </i> most AS’s are following the standard. </div>
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<div>And we’re not talking about single-homed AS’s using private ASNs. Those are definition excluded, because, being single homed, there is only one path to their prefixes.</div>
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<div dir="ltr"><font color="#000000"><span style="caret-color: rgb(0, 0, 0); background-color: rgba(255, 255, 255, 0);">Any organization that has multiple sites with their own Internet<br>
connections, would then need an AS number for each site.</span></font></div>
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What are you talking about? Do you use multi homed BGP? If so, I’d expect you to know that an organization with multiple sites having their own Internet still uses a single AS. They have IGP paths to route traffic between sites (e.g., by using dedicated circuits).<br>
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<div dir="ltr"> -mel </div>
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On May 30, 2019, at 3:55 PM, Thomas Bellman <<a href="mailto:bellman@nsc.liu.se">bellman@nsc.liu.se</a>> wrote:<br>
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<div dir="ltr"><span>On 2019-05-30 20:00 +0000, Mel Beckman wrote:</span><br>
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<blockquote type="cite"><span>I’m sure we can find corner cases, but it’s clear that the vast</span><br>
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<span> ^^^^^</span><br>
<blockquote type="cite"><span>majority of BGP users are following the standard.</span><br>
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<span>"Citation needed". :-) How is it clear that the vast majority are</span><br>
<span>following this?</span><br>
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<span>I wouldn't be at all surprised if it *is* literally true; e.g,</span><br>
<span>quite a lot of BGP users are probably single-homed and thus are</span><br>
<span>forced to use private ASNs for talking BGP to their ISP; and lots</span><br>
<span>of BGP users are also single-site, and don't engage in traffic</span><br>
<span>engineering.</span><br>
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<span>But those cases are also not very interresting for this. It is</span><br>
<span>more interresting to look at those that according to RFC 1930</span><br>
<span>*should* use multiple ASNs; how many of those *do* have separate</span><br>
<span>ASNs for each group of prefixes with a "single and clearly defined</span><br>
<span>routing policy", and how many *don't*?</span><br>
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<span>Any organization that has multiple sites with their own Internet</span><br>
<span>connections, would then need an AS number for each site. How many</span><br>
<span>people follow that? Can I get multiple ASNs from RIPE/ARIN/et.c</span><br>
<span>for this case? (That's an honest question; the policies I found</span><br>
<span>does mention sites or connected groups of networks, but they also</span><br>
<span>mention organizations in a way that makes me wonder.)</span><br>
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<span>As others have mentioned, if you do traffic engineering by announcing</span><br>
<span>prefixes with e.g. different BGP communities, or different amounts of</span><br>
<span>ASN prefixing, you should according to RFC 1930 get a separate ASN</span><br>
<span>for each unique combination of communities and ASN prefixing. Will</span><br>
<span>RIPE/APNIC/et.c grant us multiple ASNs for that? I kind of suspect</span><br>
<span>that we would be told to get lost if we requested 256 ASNs from RIPE</span><br>
<span>for traffic engineering our /16 into 256 /24:s...</span><br>
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<span> /Bellman</span><br>
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